Method of extracting copper from ores.



GEORGE D. VAN ARSDALE, OF EAST ORANGE, NEW JERSEY.

METHOD OF EXTRACTING COPPER FROM ORES.

No Drawing.

tain new and useful Improvements in Methods of Extracting.. Copper fromOres, of whichthe followin is a specification.

My invention re ates to an improvement in a method of leaching copperores and separating metallic copper from the resulting solution byelectrolysis. The solution preferably used is one containing copper inthe form of sulfate, together with other sulfates which will be obtainedby leaching copper ore containing iron by the use of diluted sulfuricacid. I

Heretofore sulfur dioxid has been added to such solutions beforeelectrolyzing for the purpose of reducing polarization, and sumlarmethods using chlorid solutions have been proposed. None of thesemethods has been commercially successful and I have dis covered thatunder the conditions present in employing them a part or all of thecopper is precipitated as sulfid compounds of copper and not as metalliccopper. This disadvantageousfeature 1S caused by electrolytic hydrogenevolved at the cathode reacting with the sulfur dioxid present andforming hydrogen sulfid which then precipitates copper as sulfid. Thisside reaction is extremely undesirable as sulfid of copper is notmarketable as such and requires further expensive treatment before itcan be sold. I have discovered that such deposition of sulfid coppercompounds can be prevented and will describe herein my novel method ofleaching copper ores and separating metallic copper from the solutionobtained.

'I prefer to use a solution of copper sulfate. This may be made eitherby dissolving the requisite amount of copper sulfate in Water or bymaking a solution of copper sulfate from copper ores which have beenroasted. Such solutions contain certain amounts of ferrous sulfateswhich in former practice has.been undesirable, but 'hich according tomyimproved method is made a desirable factor. The next step is to add inany of the Well known ways, sulfur dioxid, and the resulting solutiontreated elcctro' lytically. A. function of the sulfur dioxid is not onlyto act as a depolarizer but also to reduce any ferric sulfate present inthe solutions to ferrous salts which also tend to pre- Patented Dec. 1,1914:.

Application filed May 16, 1912. Serial No. 697,784.

vent polarization at the anode, the ferrous sulfate combining withnascentoxygen at the anode to form ferric sulfate. The precipitation ofsulfid of copper might be avoided by using an electrolytic cell which isdivided by a porous diaphragm into two compartments and not allowingsulfur di oxid to be present in the cathode compartment. But I prefer towork without a diaphragm and to regulate the voltage and speed ofdeposition so that copper only is separated and not hydrogen or sulfidof hydrogen. With a 10% solution of copper sulfate containing sulfurdioxid sufficient to prevent polarization and to reduce all salts ofiron to the ferrous state, I find that with about ten am eres per squarefoot in voltage between and 1.2 volts it is possible to precipitateabout 80% of the copper before the formation of the sulfids commencesand I prefer therefore to stop at that point. The solution afterprecipitating 80% of the cop per will then contain free sulfuric acidand the remaining copper and used for leaching copper from more ores. Indoing this the leaching is so carried on as to approximately regeneratethe original solution which is then again subjected to the sameoperations as before.

The voltages and amperage specified are given as an example of a givencase, but may be varied under differing conditions; but

It is to be understood that the foregoing description is general andthat details may vary considerably in different cases. Other methods andconditions necessary to avoid the sulfid precipitation and for otherreasons may be required and possible. For example, the electrolyte maybe heated and circulated during the electrolytic treatment.

\Vhat I claim is:

l. The herein described method of ex-.

tracting copper from ores which comprises leaching the ores with asolution containing :-.ulfuric acid, adding sulfur dioxid to theresulting solution, electrolyzing said solution,

and controlling the electrical conditions to cause the deposition of thecopper either in the form of metallic copper or copper sulfid.

2. The herein described method of extracting copper from ores, whichcomprises leaching the ores with a solution containing sulfuric acid,adding sulfur dioxid to the resulting solution, electrolyzing saidsolution, controlling the electrical conditions to cause the depositionof a large portion of the copper in the form of metallic cop er, andstopping the electrolysis before sul (1 compounds begin to beprecipitated.

3. The herein described method of extracting copper from ores whichcomprises leaching the ores with a solution containing sulfuric acid andsulfates to form a copper sulfate solution containing substantially tenper cent. copper, adding sulfur dioxid to such solution to preventpolarization, electrolyzing said solution, controlling the electricalconditions to permit the deposition of r the metallic copper, andstopping the electrolysis when approximately eighty per cent. of thecopper has been removed and before sulfid compounds begin to beprecipitated.

4:. The herein described method of extracting copper from ores whichcomprises leaching the ores with a solution containingsulfuric acid andsulfates, adding sulfur dioxid to the resulting solution, electrolyzingsaid" In witness whereof, I have hereunto set I my hand this 15th day ofMay 1912.

GEORGE D. VAN ARSDALE. Witnesses:

WILLIAM J. SPERL, ERNEsr W. MARSHALL.

Gopies of this patent may be obtained for five cents each. by addressingthe Commissioner of Patents,

' Washington, D. G. a

